Field of the Invention
This invention relates to a gear machining device and a gear machining method for machining a gear by cutting machining by synchronizing a rotation of a machining tool with a rotation of a workpiece to be machined.
Description of Related Arts
As an effective measure for machining both internal and external teeth by cutting machining, a machining device disclosed in a Patent Document 1 (JPH01-159126 A) may be exampled. The machining device according to this conventional technology produces gear teeth by cutting with synchronized rotations of a workpiece and a machining tool with high speeds, feeding the machining tool in a rotation axis direction of the workpiece. The workpiece is rotatable about a rotation axis and the machining tool is, for example, a cutter with a plurality of cutting blade portions, which is rotatable about a rotation axis inclined with a predetermined angle relative to the rotation axis of the workpiece, i.e., rotatable about a rotation axis having an intersecting angle relative to the rotation axis of the workpiece.
However, according to the conventional machining device, since the plurality of cutting blade portions contacts with the workpiece at the same time, the cutting resistance tends to be increasing which may generate self-induced vibrations upon cutting operation. This may worsen the tooth trace accuracy (generation of waviness of the tooth trace). As a countermeasure to this, the diameter of the machining tool may be lessened to reduce the number of contacts of the blade portions with the workpiece. However, in such case, the rigidity of the machining tool may be deteriorated.
Accordingly, in order to overcome such issues, a machining method has been proposed in a Patent Document 2 (JP2005-335061 A), wherein the machining tool is moved relative to the workpiece with a variable feeding speed in a feeding route direction along the tooth surface. According to this machining method, since the interval between fine machining scratches becomes irregular along the surface of each tooth, it is possible to reduce noise generated upon meshing between the machining tool and the workpiece, that is, self-induced vibrations during cutting. Further, a Patent Document 3 (JP4468632 B) discloses a setting method of the intersecting angle by determining the position and the rotational angle of the machining tool for producing the internal gear teeth by machining.